This invention relates generally as indicated to a cushioning conversion machine and method. More particularly, this invention relates to improved forming assemblies and/or forming steps for cushioning conversion machines and methods.
In the process of shipping an item from one location to another, a protective packaging material is typically placed in the shipping case, or box, to fill any voids and/or to cushion the item during the shipping process. Some conventional commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to adequately perform as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and/or plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable and thus they cannot avoid further multiplying our planet""s already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
These and other disadvantages of conventional plastic packaging materials has made paper protective packaging material a very popular alternative. Paper is biodegradable, recyclable and renewable; making it an environmentally responsible choice for conscientious industries. While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a relatively low density pad-like cushioning dunnage product. This conversion may be accomplished by a cushioning conversion machine, such as those disdosed in U.S. Pat. Nos. 4,026,298; 4,085,662; 4,109,040; 4,237,776; 4,717,613; 4,750,896; 4,884,999; 5,061,543; 5,188,581 and/or 5,607,383. (These patents are assigned to the assignee of the present application and their entire disclosures are hereby incorporated by reference.)
Each of the cushioning conversion machines disclosed in the above-identified patents includes a conversion assembly which converts sheet-like stock material into a three-dimensional strip of cushioning. The conversion assembly includes a forming assembly which forms the sheet-like stock material into a strip of stock material having lateral pillow-like portions. The conversion assembly also includes a feeding assembly which is positioned downstream of the forming assembly and which pulls the stock material through the forming assembly.
The forming assemblies in the above-identified patents each comprise an external forming device and an internal forming device which are positioned within a common envelope defined by the machine""s housing. The stock material travels through the external forming device and around the internal forming device as it passes through the forming assembly to form the strip of stock material. The external forming device is a converging chute having an inlet, an outlet and substantially continuous walls therebetween which define a turning space. In the external forming device (or chute) disclosed in U.S. Pat. No. 5,607,383, the upstream edges of certain walls are outwardly flared in a trumpet-like fashion to facilitate passage of the stock material into the turning space and/or to prevent any tears in the stock material during this passage.
In U.S. Pat. Nos. 4,026,298; 4,085,662; 4,109,040 and/or 4,237,776, the internal forming device (called a pusher mechanism) includes a body which is made of a bar-like material, such as metal rod, and which is triangular shaped when viewed from the top. During the forming process, converging leg portions of the body define a co-planar turning perimeter around which lateral regions of the stock material are inwardly turned. These converging leg portions and also lateral cross-leg portions form a co-planar holding surface that holds central regions of the stock material as its lateral regions are inwardly turned. The body is positioned entirely within the external forming device with its downstream end being positioned slightly upstream of the chute""s outlet.
In U.S. Pat. No. 4,717,613, the internal forming device (called a forming frame) includes a planar body and three perpendicular ribs, all of which are made of a bar-like material, such as metal rod. The body is V-shaped when viewed from the top. The ribs are U-shaped when viewed from the device""s upstream end and decrease in height and width in the downstream direction. During the forming process, converging leg portions of the body define a co-planar turning perimeter around which lateral regions of the stock material are inwardly turned and bottom leg portions of the ribs define a co-planar holding surface that holds central regions of the stock material. The body and ribs are all positioned entirely within the turning space of the external forming device and the device""s downstream end (i.e., the downstream end of the V-shaped body) is located just upstream of the chute""s outlet.
In U.S. Pat. No. 4,750,896, the internal forming device (called a forming frame) has a construction similar to the internal device disclosed in U.S. Pat. No. 4,717,613, except that it includes only two ribs. During the forming process, converging leg portions of the device""s body define a co-planar turning perimeter and bottom leg portions of the its ribs define a co-planar holding surface. This device is positioned only partially within the chute in that it has upstream portions situated outside of the chute and downstream portions situated within the chute. The device""s downstream end is positioned within the turning space just upstream of the chute""s outlet.
In U.S. Pat. Nos. 4,884,999; 5,061,543 and/or 5,188,581, the internal forming device (called a former member) includes an elongated bar-like body having a rectangular cross-section. This internal forming device is designed to coact with a smaller chute to produce a narrower strip of cushioning. In any event, during the conversion process, the top lateral edges of the body define a co-planar turning perimeter and the bottom surface of the body defines a co-planar holding surface. The upstream portions of the rectangular body are positioned upstream of the chute""s inlet and the device""s downstream end is positioned just upstream of the chute""s outlet.
In U.S. Pat. No. 5,607,383, the internal forming device (called a forming member) comprises a first leg portion, a second leg portion and a bight portion which performs as a living hinge between the leg portions. During the forming process, the bottom surface of the second leg portion defines a co-planar holding surface that holds the central region of the stock material as its lateral regions are inwardly turned. The first leg portion is attached to the chute""s top wall along a laterally center line thereof, the bight portion is positioned upstream of the chute""s inlet, and the second leg portion extends from the bight portion into the chute""s turning space. The device""s downstream end (i.e., the downstream end of the second leg portion) is positioned within the turning space just upstream of the chute""s outlet.
Thus, over the years, forming assemblies have been modified, improved, or otherwise changed. Despite these past modifications, improvements, and changes, the inventors believe that a need remains for further cushioning conversion machines and methods which produce cushioning strips having enhanced qualities and/or having different shaped cross-sectional geometries. Moreover, irrespective of particular qualities and geometries, environmental and other concerns provide a constant desire for new cushioning products and for machines/methods for producing such products.
The present invention provides a cushioning conversion machine including a conversion assembly which converts sheet-like stock material into a three-dimensional strip of cushioning. The conversion assembly includes a forming assembly which forms the sheet-like stock material into a strip of stock material having lateral pillow-like portions. Preferably, the conversion assembly also includes a feeding assembly that feeds the stock material through the forming assembly. More preferably, the feeding assembly is positioned downstream of the forming assembly and pulls the stock material through the forming assembly.
The forming assembly comprises an external forming device and an internal forming device that are preferably positioned within a common envelope defined by the machine""s housing. The stock material travels through the external forming device and around the internal forming device as it passes through the forming assembly to form the strip of stock material.
The external forming device has an inlet, an outlet and surfaces therebetween which define a turning space. The surfaces of the external forming device radially restrict the stock material as it travels through the turning space to cause inward turning of the lateral regions of the stock material to form the strip of stock material. Preferably, the external forming device is a chute having substantially continuous walls extending between the inlet and the outlet. More preferably, the external forming device is a converging chute whereby its inlet is of greater area than its outlet and its walls taper inwardly in the downstream direction.
According to one preferred embodiment of the invention, the internal forming device has at least one interacting portion which is positioned downstream of the outlet of the external forming device and which is positioned to internally interact with lateral portions of the strip of stock material. In this manner, the strip of stock material has a certain cross-sectional geometry when it emerges from the outlet of the external forming device and the interacting portions then internally reshape this cross-sectional geometry. An extruding device may be positioned downstream of the outlet of the external forming device. Such an extruding device would be used to externally coact with the interacting portion(s) to re-shape the cross-sectional geometry of the strip of stock material.
According to another preferred embodiment of the invention, the internal forming device comprises a pair of mandrel portions symmetrically positioned relative to the turning space defined by the external forming device. The mandrel portions are located on at least one supporting portion and the mandrel portions have a greater cross-sectional area than the supporting portion(s). The mandrel portions may be positioned downstream of the outlet of the external forming device or may be positioned within the turning space of the external forming device (i.e., upstream of the outlet). In the latter case, the mandrel portions may be positioned adjacent the outlet or may be positioned approximately intermediate the inlet and the outlet of the external forming device.
According to another preferred embodiment of the invention, the internal forming device comprises a least one interacting portion which interacts with the strip of stock material to effect its cross-sectional geometry and a supporting portion which is used to mount the interacting portion(s). The supporting portion is mounted to the machine""s housing downstream of the outlet of the external forming device. The position of the interacting portion(s) is preferably downstream of the outlet of the external forming device. Additionally or alternatively, the interacting portions preferably comprise a pair of mandrel portions symmetrically positioned relative to the turning space.
According to another preferred embodiment of the invention, the internal forming device has portions which define a turning perimeter around which lateral regions of the stock material are inwardly turned. The turning perimeter includes coplanar portions and at least one mandrel portion which transversely projects beyond the coplanar portions. Preferably, the internal forming device comprises a pair of mandrel portions laterally symmetrically positioned relative to the turning space and the coplanar portions comprise a pair of mandrel-supporting portions extending through the turning space.
According to another preferred embodiment of the invention, the internal forming device comprises at least one portion defining a holding surface and a mandrel portion attached to the downstream end of this at least one portion. The holding surface holds a central region of the stock material as it travels through the turning space. The mandrel portion has a lateral section which projects laterally outward from the downstream end of the portion. The mandrel portion may be positioned downstream of the outlet of the external forming device or may be positioned upstream of the outlet of the external forming device (i.e., within the turning space). The mandrel portion may also include wing sections extending from the lateral mandrel section.
According to another preferred embodiment of the invention, the internal forming device has portions which define a holding surface that holds central regions of the stock material as it travels through the turning space. The holding surface includes at least one protrusion which projects beyond a plane extending from the upstream edge of the holding surface to the downstream edge of the holding surface. The holding surface may be defined by a leg portion which longitudinally extends through the center of the turning space and a mandrel portion attached to the downstream end of the leg portion. Alternatively, the holding surface may be defined by ribs extending downward from a V-shaped body.
According to yet another preferred embodiment of the invention, the internal forming device includes a pair of leg portions and a nose portion which joins together the downstream ends of the legs portion. The leg portions extend longitudinally through the turning space and laterally converge towards each other. The nose portion has a transverse linear section positioned centrally relative to the turning space and extending in the lateral transverse direction. Preferably, the transverse linear section extends approximately two inches in the lateral transverse direction.
These and other features of the invention are fully described and particularly pointed out in the claims. The following descriptive annexed drawings set forth in detail certain illustrative embodiments, these embodiments being indicative of but a few of the various ways in which the principles of the invention may be employed.